Ms. Yin comments, "As one crucial step of achieving controllable quantum devices, we have developed an unprecedented level of manipulating light on a superconducting chip. In our experiment, we caught and released photons in and from a superconducting cavity by incorporating a superconducting switch. By controlling the switch on and off, we were able to open and close a door between the confined cavity and the road where photons can transmit. The on/off speed should be fast enough with a tuning time much shorter than the photon lifetime of the cavity."

The UCSB superconducting quantum chip was chilled to three-hundreths of a degree Kelvin.

There were some rather significant technical hurdles that are required to achieve the team's impressive results. The approximately 1 sq. inch chip had to be chilled to -273.12 ºC -- or about two-hundredths of a degree Kelvin above absolute zero.

The next step is to tune the device to transfer controlled-state photons between two cavities. That will be a critical step towards quantum memory or a cavity-based quantum computing device.

Just .03K. Capital K, no 'º'. It's capital because it's named after a person: William Thomson, 1st Baron Kelvin. You drop the º because unlike degrees C or F, Kelvins are a direct measurement of the thermal energy of a system (something that is 20 ºC cannot be said to be 2 times warmer than something that is 10 ºC). Basically, the º calls out that the scale is arbitrary, which isn't the case for Ks.